The present invention relates to a cylindrical body appearance inspection apparatus for inspecting a flow, crack or pinhole on a surface of a cylindrical body such as mechanical part, e.g. bearing roller, or uranium pellet for use as nuclear fuel.
A prior art cylindrical body appearance inspection apparatus such as that disclosed in the article entitled "Automatic Inspection of Fuel-Element Pellets" (Metrology and Inspection, Autumn 1969) detects any chipping on a surface of a pellet by moving the pellet at a constant speed in a multi-jet air-gauging ring with the aid of push-through plunger in addition to a walking beam and senses any corner chipping of the pellet by carrying the pellet between two sensing heads which couple electro-pneumatic cells, by a walking beam transfer mechanism. However, since the prior art apparatus detects the chip of the cylindrical body by air-gauging method, it has a low resolution power and could not detect a crack of very small width. Further, because of the air-gauging method, it is difficult to detect a small chip on an edge of an end surface of the pellet or at an end of a cylindrical surface, that is, a chip close to a corner of the pellet.